There are fears that more members of an Assyrian Christian community in north-eastern Syria were abducted by Islamic State militants than at first thought.

Initial reports had put the number of missing at 90, but one activist said as many as 285 people had been seized on Monday in Hassakeh province.

Efforts to try to negotiate their release are reported to be under way.

Some 1,000 local Assyrian families are believed to have fled their homes in the wake of the abductions.

Kurdish and Christian militia are battling IS in the area, amid reports of churches and homes having been set ablaze.

Thousands of Christians in Syria have been forced from their homes by the threat from IS militants.

In areas under their control, Christians have been ordered to convert to Islam, pay jizya (a religious levy), or face death. IS militants in Libya also recently beheaded 21 Egyptian Coptic Christians.

Kurdish offensive

The Assyrians were seized by the militants as they swept into 12 villages along the southern bank of the Khabur river near the town of Tal Tamr before dawn on Monday.

The Syrian Observatory for Human Rights, a UK-based activist group, said at least 90 people had been abducted, most of them women, children and the elderly.

However, the Syriac National Council of Syria put the figure as high as 150, while Afram Yakoub of the Assyrian Federation of Sweden said sources on the ground had told him that up to 285 people were missing, including 156 from the village of Tal Shamran and 90 from Tal al-Jazira.